netdev - [PATCH bpf-next v4 0/2] Optimize bpf_redirect_map()/xdp_do

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Message-Id: <20210226112322.144927-1-bjorn.topel@gmail.com>
Date:   Fri, 26 Feb 2021 12:23:20 +0100
From:   Björn Töpel <bjorn.topel@...il.com>
To:     ast@...nel.org, daniel@...earbox.net, netdev@...r.kernel.org,
        bpf@...r.kernel.org
Cc:     Björn Töpel <bjorn.topel@...il.com>,
        bjorn.topel@...el.com, maciej.fijalkowski@...el.com,
        hawk@...nel.org, toke@...hat.com, magnus.karlsson@...el.com,
        john.fastabend@...il.com, kuba@...nel.org, davem@...emloft.net
Subject: [PATCH bpf-next v4 0/2] Optimize bpf_redirect_map()/xdp_do_redirect()

Hi XDP-folks,

This two patch series contain two optimizations for the
bpf_redirect_map() helper and the xdp_do_redirect() function.

The bpf_redirect_map() optimization is about avoiding the map lookup
dispatching. Instead of having a switch-statement and selecting the
correct lookup function, we let bpf_redirect_map() be a map operation,
where each map has its own bpf_redirect_map() implementation. This way
the run-time lookup is avoided.

The xdp_do_redirect() patch restructures the code, so that the map
pointer indirection can be avoided.

Performance-wise I got 3% improvement for XSKMAP
(sample:xdpsock/rx-drop), and 4% (sample:xdp_redirect_map) on my
machine.

More details in each commit.

@Jesper/Toke I dropped your Acked-by: on the first patch, since there
were major restucturing. Please have another look! Thanks!

Changelog:
v3->v4:  Made bpf_redirect_map() a map operation. (Daniel)

v2->v3:  Fix build when CONFIG_NET is not set. (lkp)

v1->v2:  Removed warning when CONFIG_BPF_SYSCALL was not set. (lkp)
         Cleaned up case-clause in xdp_do_generic_redirect_map(). (Toke)
         Re-added comment. (Toke)

rfc->v1: Use map_id, and remove bpf_clear_redirect_map(). (Toke)
         Get rid of the macro and use __always_inline. (Jesper)

rfc: https://lore.kernel.org/bpf/87im7fy9nc.fsf@toke.dk/ (Cover not on lore!)
v1:  https://lore.kernel.org/bpf/20210219145922.63655-1-bjorn.topel@gmail.com/
v2:  https://lore.kernel.org/bpf/20210220153056.111968-1-bjorn.topel@gmail.com/
v3:  https://lore.kernel.org/bpf/20210221200954.164125-3-bjorn.topel@gmail.com/

Cheers,
Björn

Björn Töpel (2):
  bpf, xdp: make bpf_redirect_map() a map operation
  bpf, xdp: restructure redirect actions

 include/linux/bpf.h        |  26 ++----
 include/linux/filter.h     |  39 +++++++-
 include/net/xdp_sock.h     |  19 ----
 include/trace/events/xdp.h |  66 ++++++++-----
 kernel/bpf/cpumap.c        |  10 +-
 kernel/bpf/devmap.c        |  19 +++-
 kernel/bpf/verifier.c      |  11 ++-
 net/core/filter.c          | 183 ++++++++++++-------------------------
 net/xdp/xskmap.c           |  20 +++-
 9 files changed, 195 insertions(+), 198 deletions(-)

base-commit: 9c8f21e6f8856a96634e542a58ef3abf27486801
-- 
2.27.0